The present invention relates to power steering apparatus.
A technique relating to power steering apparatus is disclosed in Japanese Patent Application Publication No. H11-29056 (Patent Document 1). Patent Document 1 discloses an electric motor-driven power steering apparatus having a plurality of assist characteristics, in which, in order to smoothly switch from one assist characteristic to another without giving a sense of incongruity to the driver during switching, a characteristic used before switching of the characteristics and a characteristic to be used after the switching are simultaneously calculated and processed by using a transition coefficient, thereby attaining smooth switching between the assist characteristics.
[Patent Document 1] JP H11-29056
With the technique disclosed in the above-described Patent Document 1, however, when the driver switches from an assist characteristic providing a large assist quantity to an assist characteristic providing a small assist quantity during turning the steering wheel, he or she may feel a sense of incongruity due to a lack of assist quantity. Conversely, when the driver switches from an assist characteristic providing a small assist quantity to an assist characteristic providing a large assist quantity during returning the steering wheel, he or she may feel a sense of incongruity due to an excess of assist quantity.
The present invention has been made in view of the above-described problem.
Accordingly, an object of the present invention is to provide a power steering apparatus capable of switching between assist characteristics without giving a sense of incongruity to a driver.